1. Field of the Invention
The present invention relates to an integrated thin film head comprising an MR sensor and the manufacturing method thereof, and particularly to an integrated thin film head that can prevent short-circuit among thin films and a method of manufacturing the same head.
2. Description of the Related Arts
An integrated thin film head comprising an MR (Magneto-Resistive Effect) sensor that is generally used in a magnetic disc apparatus integrates an inductive head element for data recording and an MR sensor for data reproduction and an electric resistance between the connecting pinouts of this MR sensor layer is desired to be as lower as possible in order to suppress thermal noise and prevent drop of S/N. As the technique to lower the electric resistance between the connecting pinouts of this MR sensor layer, the Japanese Unexamined Patent Publication No. H11-238211, for example, discloses a technique to provide a lead layer (lead conductive layer) of the double-layer structure for the MR sensor and provide a second lead conductive layer near to the MR sensor.
On the other hand, in the thin film head in the recent years, an interval between a shield layer and the MR sensor tends to be narrowed with increase of magnetic recording density and this interval is generally determined depending on the thickness of non-magnetic layer formed on and/or under the MR sensor.
When the interval between the shield layer and MR sensor is narrowed in the integrated thin film head of the related art, here rises a discrepancy that thin film manufacturing yield is lowered because adhesion of non-magnetic layer for the sputtering is deteriorated due to a level-different area (stepped area) between the lead layer and upper lead layer, and thereby a thinner area may be susceptible to cause of a short-circuit between the shied layer and upper lead layer.
In view of overcoming this discrepancy, the Japanese Unexamined Patent Publication No. H6-333215, for example, proposes a structure wherein the stepped area of lead layer is formed as a very smooth tapered-shape to improve coverage of an insulation layer (upper shield gap) and thereby generation of short-circuit between the lead layer and upper shield layer can be prevented.
In more practical, the integrated thin film head disclosed in above patent unexamined application comprises, like FIG. 3 illustrating the plan view of the head, an MR sensor layer 1, a couple of lead layers 2 connected across the MR sensor layer 1, an upper lead layer 3 conductive to the lead layer 2, and a lower shield layer 4 and an upper shield layer 5 for magnetically shielding these layers. In FIG. 3, the MR sensor layer 1, lead layer 2, upper lead layer 3 and lower shield layer 4 are illustrated in perspective through a write element and upper shield layer 5.
As illustrated in FIG. 2 illustrating the A—A cross-sectional view of FIG. 3, this integrated thin film head is formed by forming the lower shield layer 4 and a stepped area filler material 41 of the lower shield layer on a substrate and an undercoat layer (not illustrated) formed on the substrate, stacking a lower readgap layer 7 on the lower shield layer 4 and the filler material 41, forming the MR sensor layer 1 on such gap layer, forming a lead layer 2 joined on the sloping surface of the MR sensor layer 1, forming an upper lead layer 3 by the lift-off method on the lead layer 2 and moreover stacking thereon an upper readgap layer 6 and an upper shield 5.
The integrated thin film head disclosed in the Japanese Unexamined Patent Publication No. H11-238211 has a problem, when it has employed a structure that the upper lead layer (second lead conductive layer) is provided near the MR sensor layer, that a large stepped area is generated in the side of the MR sensor layer due to the thickness of the lead layer (first lead conductive layer) and the upper lead layer (second lead conductive layer), this stepped area deteriorates adhesion of the lead gap layer and such deterioration is inferior to the gap layer that is narrowed with high density recording.
Moreover, the integrated thin film head forming the smooth tapered-area disclosed in the Japanese Unexamined Patent Publication No. H6-333215 that will be explained layer also has a problem that the part where the smooth tapered-area (sloping area of the upper readgap layer 8 in FIG. 2) is formed thin, it is difficult in this case to reduce the electric resistance and it also becomes difficult to maintain the stable resistance in such smooth tapered-area because the tapering shape is fluctuated.
In other words, the integrated thin film head of the related art that will be explained later has a problem that since the upper lead layer 3 is formed on the lead layer 2, thickness c of the stepped area at the stacking part of the lead layer and upper lead layer becomes equal to the sum of the lead layer thickness a and upper lead layer thickness b, the thickness c (=a+b) becomes larger than that when there is no upper lead layer 3, therefore adhesion of the upper readgap layer 6 to the upper corner part 8 of the upper lead layer is rather deteriorated than that at the flat area, and thereby it will be susceptible to cause of short-circuit with the upper shield layer 5.
As explained above, the integrated thin film head of the related art has a problem that a resistance value across the connecting pinouts of the head having the structure that the upper lead layer is formed near the MR sensor layer becomes small and it is difficult to obtain the stable resistance value.